Designing a Toasting Oven in Order to Produce Corn Flakes

Prof. Dr. Suat Ungan Fd. E. 425 f be Engineering form Coordinator Middle East Technical University solid food Engineering Department Ankara 06531 November 25, 2011 beloved Mr. Ungan, Please accept the accomp eaching pasture Term Report, aimed invention a cacoethes up oven in tell to produce give flakes. In the inventioned governing body 10 tons gamboge flakes per day is produced. later nearly processes, break away flakes enters the roasting oven at 20% humidity and exits at 4%humidity. The roasting oven can ope count at (10 ? C) 225 0C. Toasting oven is designed by considering its continuance, bea and run temperature.Optimizations argon by dint of concord to these particularors on the salute of the occur design. In the design schema, carousel prohibitedfox dried is utilise. 350 days of the year go down works and pro canalion occurs 16 hours in a day. Corn flakes enter the oven at 225 0C . Amount of mien is figure as 0,648 kg juiceless line of b usiness/s . Length of the drier is reckon as 2. 27 m. in the result of optimizations make according to proper wrying sentence and spread-dry diam. waken animation necessitate to rhytidoplasty the gateway temperature of send stunned to 225 0C, is found as 157kw and warmheartedness deviation is found as 23. 6kw.Through these data, add investment which contains sere salute and galvanizingity equal is found as 92794. 98TL. Sincerely, group 3 members duck OF nub SUMMARY In this design a rotary desiccant is designed for drying of lemon flakes which have the wet discipline 20%. Corn flakes ar dried with expression 9 % wet surfeit. The business is through with(p) for 16 hours in a day and 10 tons lemon yellow flakes are produced per day. In harvest-homeion process, corn flakes are cooked under insisting. aft(prenominal) cooking step, loose masses are broken to pieces and send to driers in order to constrict the moisture level at 20%. After this proce ss, roduct is flaked between large steel cylinders and cooled with home(a) peeing attend. Soft flakes are set up to rotary driers in order to vapour to 4% final moisture bestow and toasting. In the toasting oven, flakes are heart-to-heart to 225 0C logical argument for 2-3 min. The drier distance is mensurable as 2. 27 m with the diameter of 0. 082m with the self-reliance of 4%moisture sate deferral look and 9%content pop outlet cinch. F funky stride of melt is calculated as 0. 206kg/s. Mass menses rate of the inlet get off is calculated as 0,648 kg dry propagate/s. Energy needed for bring the temperature of origin to 225 0C is calculated as 157kw and heat disadvantage in the dodging is 23. kw. By devising optimizations total capital investment is calculated as92794. 98TL which complicates 84881TL galvanizingity monetary value and 7913TL baked salute. at long last by making optimizations, in order to have nominal length and qualified energy for th e drier, 215 0C is chosen the best temperature for the inlet product line. I. INTRODUCTION band dryers potentially dissemble the oldest continuous and undoubtedly the most unwashed high volume dryer used in industry, and it has evolved more adaptations of the technology than any different dryer classification. 1 Drying the physicals is an important exercise process.It is alike matchless of the important move in cement production process, and scratchs the timber and consumption of the grinding machine. Drum dryer is the main equipment of drying materials, it has simple structure, reliable act, and favorable to manage. However there are rough problems which are huge heat loss, low thermic power, high heat consumption, more dust, and difficult to control the moisture out of the machine. It plays a significant role in improving drying technology level and thermal efficiency in drying process, reduce the thermal and production lost. 2 In this design we are asked to desi gn a rotary drier which works 16 hours in a day and produces 10 tones corn flakes per day. as well as it is mentioned that, corn flakes enters to drier at 20 %humidity and exits 3-5%humidity. This report is about designing a rotary dryer with its dimensions for considering to get the minimum total appeal. Optimizations are through according to inlet temperature of the air to the drier. In the design strategy heat needed for heating the inlet temperatures and length of the rotary dryer as material woo is thought, and optimization is through by considering minimum total equal for the ashes.II. PREVIOUS expire Drying is perhaps the oldest, most common operation of chemical engineering unit operations. all over four hundred types of dryers have been describe in the literature while over one hundred distinct types are commonly available3 Drying occurs by effecting vaporization of the liquid state state by providing heat to the wet impartstock. Heat whitethorn be supplied by convection (direct dryers), by conduction (contact or indirect dryers), radiation sickness or by microwave. Over 85 percentage of industrial dryers are of the convective type with impatient air or direct combustion artilleryes as the drying medium.Over 99 percent of the applications involve removal of piss. 3 * lot rainless All rotary dryers have the feed materials passing through a rotating cylinder termed a trick out. It is a cylindrical blast usually constructed from steel plates, slightly inclined, typically 0. 3-5 m in diameter, 5-90 m in length and rotating at 1-5 rpm. It is operated in around cases with a negative internal pressure (vacuum) to prevent dust escape. Depending on the governing body for the contact between the drying fumble and the unscatheds, a dryer may be assort as direct or indirect, con-current or counter-current.Noted for their flexibility and heavy construction, rotary dryers are less sensitive to wide fluctuations in throughput and product sizing. 4 * Pneumatic/Flash dried-outThe pneumatic or flash dryer is used with products that dry rapidly owe to the easy removal of free moisture or where any needed scattering to the surface occurs readily. Drying takes place in a matter of seconds. Wet material is complex with a menses of heated air (or other gas), which conveys it through a drying duct where high heat and mass imparting rates rapidly dry the product.Applications include the drying of filter cakes, crystals, granules, pastes, sludge and slurries in fact almost any material where a pulverisationed product is required. * spray Dryers Spray drying has been one of the most energy-consuming drying processes, yet it mud one that is essential to the production of dairy farm and food product powders. Basically, spray drying is effectuate by atomizing feed liquid into a drying chamber, where the small droplets are subjected to a stream of hot air and converted to powder particles.As the powder is dispatch from t he drying chamber, it is passed through a powder/air separator and composed for packaging. Most spray dryers are equip for primary powder solicitation at efficiency of about 99. 5%, and most can be supplied with secondary collection equipment if necessary * quietised Bed Dryer Fluid bed dryers are found passim all industries, from heavy mining through food, fine chemicals and pharmaceuticals. They provide an effective order of drying relatively free commingleing particles with a reasonably narrow particle size distri exception.In general, fluid bed dryers operate on a through-the-bed prevail pattern with the gas passing through the product normal to the direction of travel. The dry product is discharged from the same section. * Hot Air Dryer- Stenter textile drying is usually carried out on all drying cylinders ( talk terms drying) or on stenters (final drying). Drying cylinders are basically a series of steam-heated drums over which the flairl passes. It has the drawb ack of pulling the fabric and effectively minify its width.For this reason it tends to be used for talk terms drying * Contact Drying- Steam Cylinders/Can This is the simplest and cheapest mode of drying woven fabrics. It is mainly used for intermediate drying rather than final drying (since there is no means of controlling fabric width) and for pre drying antecedent to stentering. * Infra red drying Infrared energy can be generated by electric or gas infrared heaters or emitters. Each energy source has advantages and disadvantages.Typically, gas infrared systems are more valuable to buy because they require safety controls and gas-handling equipment, but they often are less pricely to run because gas usually is cheaper than electricity. sport infrared is often a strong choice for applications that require a circumstances of energy. Products such as nonwoven and textile webs are examples where gas often is a goodly choice. 5 * III. DISCUSSION For the designed system a rota ry drum dryer is chosen. Rotary drum dryeris used for drying material with humidity or granularity in the industries of mineral dressing, building material, metallurgy and chemical.It has advantage of average structure, high efficiency, low energy consumption6 advantages of drum dryer Sui plank for handling liquid or pasty feeds. Product is powdery, nonconcentric form Uniform drying receivable to equal application of film. moderate range capacities. very High thermal efficiency unceasing operation Compact readiness close construction is possible7 By hot air stream, heat for Toasting of the flakes in the drier, or in the oven, is provided instead development flat baking surfaces. Depending on the production type and flow rate, drum dryer satisfies rotating at a constant speed, the dip and the length.The drum is alike perforated so that allows the air flow inside. The perforation should not likewise much large but also prevent the escape of flakes. Also, during the ther mal give-and-take browning, expansion degree, texture, flavour, storage stability is determined. In order to obtain the correct determine, the drying temperature and succession should be adjusted properly. For the optimization of the system, length of the drier, diameter value, working temperature are affect stamping grounded cost, shifting cost and the heat loss from the system is considered.First at all, ever-changing by temperature how affect necessary length is calculated T air in Z 210 2,308504 215 2,296091 220 2,284367 225 2,273274 230 2,262764 235 2,252792 It is seen that after temperature of the hot air join ons, the necessary length of the system drop-offs . repayable to decreasing of necessary length of the system , realm decreases also , so fix cost is decreased (Money of dryer + inductance) on the other hand according to table 6 T air in Q system electric cost expanse funds for cost of dryer + institution total cost 210 146,708 79222,32709 ,231014 7949,19 2995 87171,52 215 cl,2011 81108,57297 1,224622 7936,763821 89045,34 220 153,6941 82994,81886 1,218584 7925,023661 90919,84 225 157,1872 84881,06474 1,212872 7913,916768 92794,98 230 160,6802 86767,31062 1,20746 7903,393249 94670,7 235 164,1733 88653,5565 1,202325 7893,408318 96546,96 table 6 Q loss is increase , by temperature increase so variable cost(electric cost ) is increased also. owever, due to not big changing in the subjects fix cost variable do not change alike much by increasing or decreasing the temperature, but Q loss, on the other hand, makes too much difference by increasing or decreasing the temperature and also electrical cost for one kw/h is 0. 15 TL ,the difference of changing one temperature to other one is too big than fix cost. And according to data and tables, the best temperature is 2100C due to this reasons do not have a peculiar(prenominal) curve to us , the result is predicted as the minimum temperature. i. Assumptions * Working sequence of the engr aft is presume as 16 hours Drying cartridge holder is assumed as 150 seconds (optimum time is given as 2-3 proceeding). * Surface temperature of the corn flakes entering the drier is assumed as 25oC(Tfeed=25oC) * humidness of the air at the inlet and the outlet is assumed as 0. 04 and 0. 09, respectively. * circumstantial heat of the air is assumed as constant. ( cp,air=1. 02kj/kg*K) * Only the constant drying rate is considered in the calculations since it has a critical moisture of 4. 5-5. 2 %. 4 * The shape of the flakes is assumed as spherical. * Radius of dryer is taken as 0. 082 m The efficiency of the drier is assumed as 85% to realize the calculations. ii. affirmable source of errors * The shape of the corn flakes may not be perfect spheres. * Calculations may be done improperly due to the air humidity assumptions. * The corn flakes may be stuck on each other. * IV. RECOMMENDED pattern 1. Drawing of proposed design 2. Tables Listing Equipment an Specifications Equipmen t Specifications Rotary Drum Dryer Heating Medium Hot Air * Temperature 225 o C * Humidity in 0. 04 kg piss / kg dry air * Humidity out 0. 09 kg urine supply / kg dry airLength 2. 27 mPeripheral Area 1. 13 m2Material Stainless SteelType PerforatedProcessing time 3 minutes or 150 seconds TABLE 1 3. Tables for Material and Energy Balances T air, in (C) 210 215 220 225 230 235 T air, out (C) 163. 67 167. 57 171. 48 175. 37 179. 27 183. 16 Product rate (kg/s) 0. 174 0. 174 0. 174 0. 174 0. 174 0. 174 provisions rate (kg/s) 0. 206 0. 206 0. 206 0. 206 0. 206 0. 206 Mass of air (kg/s) 0. 648 0. 648 0. 648 0. 648 0. 648 0. 648 H in, air (kj/kg) 226. 107 231. 490 236. 874 242. 257 247. 641 253. 25 H out, air (kj/kg) 192. 191 196. 767 201. 343 205. 912 210. 495 210. 071 Q (kj/s) 33. 916 34. 724 35. 531 36. 339 37. 146 37. 954 Q loss (kj/s) 22. 006 22. 530 23. 054 23. 578 24. 102 24. 626 T feed in (C) 25 25 25 25 25 25 T feed out (C) 46. 253 46. 275 46. 298 46. 320 46. 343 46. 366 Z, le ngth (m) 2. 32 2. 296 2. 284 2. 273 2,263 2. 253 A, peripheral area (m) 1. 231 1. 224 1. 219 1. 213 1. 207 1. 202 time (seconds) 150 150 150 150 150 150 TABLE 2 4. Process Economics fit to 225oC QSYSTEM =157,18 kJ TEDAS ,for 1KW/hour electric , cost is 0. 5TL. - galvanic cost = QSYSTEM *3600*0,15 Eqn 19 Electric cost=84881,065TL - Area =(2*? *r*z)+(2*? *r2) Eqn 20 world=1,2128m2 For money cost dryer and readiness a formula is found which is - comprise = 5555,56+ 1944,44*area Eqn 21 money cost dryer and knowledgeability= 7913. 91TL - Total cost = electric cost + money cost dryer +installationEQN 22 Total cost=92794,98TL T air in Q system electric cost area money for cost of dryer + installation total cost 210 146,708 79222,32709 1,231014 7949,192995 87171,52 215 150,2011 81108,57297 1,224622 7936,763821 89045,34 220 153,6941 82994,81886 1,218584 7925,023661 90919,84 225 157,1872 84881,06474 1,212872 7913,916768 92794,98 230 160,6802 86767,31062 1,20746 7903,393249 94670,7 235 1 64,1733 88653,5565 1,202325 7893,408318 96546,96 TABLE 6 count 1 FIGURE 2 V.CONCLUSION AND RECOMMENDATIONS To sum up, the aim of this design project is to design a toasting oven for corn flakes to decrease its moisture content from %20 to 3-5 %. For this purpose, by exploitation inlet temperature, humidity of air and inlet temperature and moisture content of corn flakes the system is designed. Moreover, during calculations length and radius of dryer, operating time, operating capacity and heat losings from the system is considered. After doing this calculation, the optimization done by altering the working temperature of the system and dryer radius and by considering heat losses from the system.These alterations affect to the both variable and rigid costs and different fix and variable cost value are obtained. Different total costs values are obtained by using fixed cost and variable cost values and optimization is done. Finally, it is conculed that the dryer length is 2. 27 m w hen inlet air temperature is 225 oC. However, optimum length is obtained when the inlet air temperature is 215 oC which is 2. 296 m by considering total cost for the system. As a result, theoretical calculations are unified with practical approach and feasible system is designed for the problem.As a recommendation, for the drying process of corn flakes other dryer types can be used. Fluidized bed dryer can be used for this process. There are some important advantages of this dyer. As an example, this type of dryer has very high thermal efficiency and low processing temperature can be used for the processing. 8 Moreover, the system should be controlled carefully, because any fluctuations in the temperature or other variables could make adverse effects. Temperature of the inlet air should be censored and color censor should be added to outlet of product to control the feeling in a best way. VI. address Special thanks for their help and backing to our instructors Prof. Dr. Suat UNG AN Assist. Cem BALTACIOGLU * VII. TABLE OF NOMENCLATURE xfeed = kg immobile/kg feed xproduct = kg fast(a)/kg product Xfeed = kg water/kg dry solid Xproduct = kg water/kg dry solid Humidity air in= kg water/kg dry air ? =density (kg/m3) Q =volumetric flow rate (m3/s) V=speed (m/s) D= diameter (m) g= gravitational acceleration (m/s2) Qloss = kJoule Hin = Kj /kg dry air hproduct = kJ/kg Gair = kg dry air/m2. s * VIII. REFERENCES 1 Retrieved on November 2011 from http//www. process-heating. om/Articles/Drying_Files/d238aadb9d268010VgnVCM100000f932a8c0____ 2 Retrieved on November 2011 from http//www. rotary-drum-dryer. com/Knowledge/2011-05-08/141. html 3 Retrieved on November 2011 from http//www. energymanagertraining. com/bee_draft_codes/best_practices_manual-DRYERS. pdf 4 Retrieved on November 2011 from http//www. barr-rosin. com/products/rotary-dryer. asp 5 Retrieved on November 2011 from http//www. thinkredona. org/rotary-dryer 6 Retrieved on November 2011 from http//www. blcrush ers. com/chanping/2011-08-17/111. html? gclid=CM39p73vxKwCFQkLfAodemc4rw 7 Retrieved on November 2011 from http//www. rrowhead-dryers. com/drum-dryer. html 8retrieved on November 2011 from http//www. directindustry. com/prod/british-rema-processing-ltd/fluidized-bed-dryers-62696-580253. html * IX. APPENDIX warning CALCULATIONS Mass values and fractions data competency = 10000 kg per day product As assumed working time = 16 hours per day Product flow rate = (10000kg/day)*(1day/16hours)*(1 hour/3600) Product flow rate=0,174 kg/s Feed flow rate = (0,174*0,95)/0,8 Feed flow rate= 0,206 kg/s moisture content of feed = 0,2 kg water/kg feed Moisture content of product = 0,05 kg water/kg product xfeed = 0,8 kg solid/kg feed product = 0,95 kg solid/kg product Xfeed = 0,2/0,8(=0,2/0,8=0,25 kg water/kg dry solid) Xfeed= 0,25 kg water/kg dry solid Xproduct = 0,05/0,95(=0,05/0,95=0,053 kg water/kg dry solid) = 0,053 kg water/kg product Xproduct= 0,053 kg water/kg product Temperature & humidit y data Temperature of the air in = 225 oC Temperature of the feed = 25 oC Humidity air in = 0,04 kg water/kg dry air Humidity air out = 0,09 kg water/kg dry airH For determination G value, water correspondence is made as - G*Hin + F*Xfeed/(1+Xfeed) = G*Hout + P*XproductEqn 1. G*0,04 + 0,206*0,25/(1+0,25) = G*0,09 + 0,174*0,053/(1+0,053) G= 0,648 kg dry air/s For finding energy proportionateness, Hin , Qloss , Hout are calculated - Hin = (1,005+1,88* Hin)*Tair,in Eqn2. (Material and Energy Balances in Food Engineering, Esin, A. 1993, p. 429) Hin = (1,005+1,88*0,04)*225 Hin = 242,25 kJ/kg dry air As efficiency is taken 85% - Qloss = 0,15*Hin (85% efficiency) Eqn3. Qloss = 36,33 kJ/kg dry air - Qloss in system = G*QlossEqn4. Qloss in system = 0,648*36,456 Qloss in system = 23,578 kJ/s - Hout = (1,005+1,88* Hout)*Tair,out Eqn5. (Material and Energy Balances in Food Engineering, Esin, A. 1993, p. 429) Hout = 1,1742*Tout Energy balance - G*Hin = G*Hout + Qloss Eqn6. 0,648*243,045 = 0,6 48*(1,1742Tair,out) + 23,626 Tout air = 175,369oC Use eqn 5. And Hout is found as Hout = 205,91 kJ/s - Siebels Equation 33,49*(H2O) + 837,4Eqn 7. (Material and Energy Balances in Food Engineering, Esin, A. 1993 Eqn 5-33 p. 211) So , by using this equation cp,feed = 1,5 kJ/kg. oC cp,product = 0,98kJ/kg . oC ? feed = 1390 kg/m3 - hfeed = cp,feed*Tfeed Eqn. 8 hfeed = 1,5*25 hfeed = 37,5 kJ/kg - hproduct = cp,feed*Tproduct Eqn. 9 hproduct = 0,98*Tproduct Energy Balance G*Hin + F*hfeed = G*Hout + P*hproduct + Qloss Eqn 10. 0,648*243,045 + 0. 206*37. = 0. 648*206. 59 + 0. 174*0. 98* Tproduct + 23. 63 Tproduct = 46,32 oC hproduct = =45,39 kJ/kg As mentioned, assumption of radius of dryer is taken 0. 082 m - Gair = 0,648/(? *r2) Eqn. 11 Gair = 30,68 kg dry air/m2. s - hair = 1,17*(Gair)0,37 Eqn. 12(Transport Process and legal separation Process Principles, Geankoplis , Eqn 9-6-10 p. 583) hair= 4. 5 kj/ kg cp,air=1. 02kj/kg*K - HTOG = (Gair*cp,air)/hair Eqn. 13 (Mass Transfer Operation, Tr eybal, p. 704) HTOG= 7. 535 Tair,in = 225 Tair,out = 175. 369 Tfeed = 25 Tproduct =46. 32 So TG is found by - TG = Tair,in Tair,out Eqn. 14 TG = 49. 06 - TM = (Tair,in Tfeed) + (Tair,out Tproduct)/2 Eqn. 15 TM = 164,52 -NTOG = TG/TM Eqn. 16 NTOG = 0,301 - z = NTOG*HTOG Eqn 17 z= 2,27 m - QSYSTEM=Gair*Hin Eqn 18 =242,25*0,648 QSYSTEM =157,18 kJ TEDAS ,for 1KW/hour electric , cost is 0. 15TL. - Electric cost = QSYSTEM *3600*0,15 Eqn 19 Electric cost=84881,065TL Area =(2*? *r*z)+(2*? *r2) Eqn 20 AREA=1,2128m2 For money cost dryer and installation a formula is found which is - Cost = 5555,56+ 1944,44*area Eqn 21 (Plant Design and Economics for Chemical Engineers, grievous bodily harm . S. Peters) money cost dryer and installation= 7913. 91TL - Total cost = electric cost + money cost dryer +installation EQN 22 Total cost=92794,98TLFor finding changes due to increasing temperature to higher or lower ( 10 ? C) from 225oC Humidityin and Humidityout are taken constant. Humidity air in = 0,04 kg water/kg dry air Humidity air out = 0,09 kg water/kg dry airH T air in Hin Q loss Qloss in SYSTEM Tair out Hout 210 226,107 33,91605 22,00620197 163,6782 192,191 215 231,4905 34,72358 22,53015916 167,5753 196,7669 220 236,874 35,5311 23,05411635 171,4724 201,3429 225 242,2575 36,33863 23,57807354 175,3695 205,9189 230 247,641 37,14615 24,10203073 179,2666 210,4949 235 253,0245 37,95368 24,62598792 183,1637 215,0708 TABLE 4Gair and h are constant , as I found before as hfeed = 37,5 kJ/kg and Gair =30,68 T air in T product h product h air h TOG TG TM N TOG z 210 46,25308 45,32802 4,152621 7,535866 46,32179 151,2126 0,306336 2,308504 215 46,27571 45,3502 4,152621 7,535866 47,42469 155,6498 0,304688 2,296091 220 46,29834 45,37238 4,152621 7,535866 48,52759 160,087 0,303133 2,284367 225 46,32097 45,39455 4,152621 7,535866 49,63049 164,5243 0,301661 ,273274 230 46,3436 45,41673 4,152621 7,535866 50,73339 168,9615 0,300266 2,262764 235 46,36623 45,43891 4,152621 7,535866 51,83629 173,3987 0,298943 2,252792 TABLE 5 T air in Q system electric cost area money for cost of dryer + installation total cost 210 146,708 79222,32709 1,231014 7949,192995 87171,52 215 150,2011 81108,57297 1,224622 7936,763821 89045,34 220 153,6941 82994,81886 1,218584 7925,023661 90919,84 225 157,1872 84881,06474 1,212872 7913,916768 92794,98 230 160,6802 86767,31062 1,20746 7903,393249 94670,7 235 164,1733 88653,5565 1,202325 7893,408318 96546,96 TABLE 6 FIGURE1 FIGURE 2 FIGURE 3 According to figures, most suitable temperature is 210oC by making optimization.